Following the media scrutiny, Swank said she "deeply regrets" attending the event and subsequently dropped her manager of eight years, Jason Weinberg and her longtime CAA agents Amie Yavor and Josh Lieberman, according to Deadline.

According to E! News, Swank received a six-figure paycheck for attending the event where she appeared on-stage to wish Kaydrov a happy birthday, saying, "Really, truly, for me this was a great honor to learn more about you and your country and what you're building. Happy birthday, Mr. President."

The group, Human Right Watch, accuse Kadyrov of various human rights violations including torture, abductions and killings.

Swank reportedly said that she was unaware of the disappearances, house torchings and extra-judicial killings reportedly orchestrated by Kadyrov, according to the Associated Press.

"I deeply regret attending this event," Swank said in a written message to the wire service on Thursday, October 13. "If I had a full understanding of what this event was apparently intended to be, I would never have gone."

The Chechen government organized a lavish concert in Chechnya's provincial capital, Grozny, on October 5. During the birthday show, according to the Associated Press, Swank said that she had been taken by the Chechen government's "passion to make peace and to make something beautiful."

The actress later claimed that her invitation to the concert made no mention of Kadyrov's birthday. Representatives for Van Damme have not commented on his attendance at the event to press outlets.

According to a statement by Human Rights Watch, "Ramzan Kadyrov is linked to a litany of horrific human rights abuses. It's inappropriate for stars to get paid to party with him. It bolsters his image and legitimizes a brutal leader and his regime. And getting paid to be part of such a lavish show in Chechnya trivializes the suffering of countless victims of human rights abuses there."

The group called for the actors and any other stars who attended the party to give back any money they received to participate at the event. In addition to Van Damme and Swank, actor Kevin Costner was invited but did not appear due to schedule conflicts with his upcoming television series "Hatfields and McCoys."

Singer Shakira and actress Eva Mendes were also reportedly invited to the event but did not attend. Human Rights Watch is an independent organization "dedicated to defending and protecting human rights," according to their website.

Prior to the event, Swank's representatives were reportedly warned about Kadyrov's human rights violations by human rights activists, according to The Hollywood Reporter. The actress' manager reportedly said in an email dated on September 26 that the Oscar-winning actress "has no current plans to attend the party."

Van Damme and Swank are not the first celebrities to come under fire for links to world leaders who have violated human rights. Beyonce, Usher and Mariah Carey were criticized for accepting money they received for performing for Moammar Gadhafi's family.